i tried to get a poll going on this recently (in this thread
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/43687-if-you-h...-af-ff-bb.html ).. Mean/mode/median seems to definetly be at 0 adjustment, with no skew towards - or +.... Tho with the lack of votes I doubt it means anthing
Personally my kit lens 18-55 ALII was adjusted to about -4.. and after the adjustment was fine irrespective of FL and distance. The 16-50 seems spot on at 0, I wouldnt be surprised if it was say +1 or -1 off cause I havent systematically tested it, but visually its so close Im in no rush adjust. Also perfect at all FL's and distances.
The 50-135 is weird. From memory I got a -2 adjustment. But its inconsistant when focusing near field. Anything 10 meters and further it seems to nail (with the -2).. Anything close and it's usually off - and it can be really far off.
Im thinking my 50-135 might be faulty in some way, but prodigital not sending me an international warranty card (when they should have), and pentax australia (cr kennedy) not caring and insisting they cant do anything without the card leaves me in a bad position. So not much I can do about it. Unless anyone out there wants to swap an international warranty card with a 2 year canadian warranty card? Umm sorry about off topic rant.